Development enhacement of electrostatic images

ABSTRACT

A PROCESS OF ENHANCING THE DEVELOPMENT OF LATENT ELECTROSTATIC IMAGES ON A SUBSTRATE WHICH COMPRISES CONTACTING THE LATENT IMAGE WITH A POWDERED PIGMENTED, FUSIBLE AND POLARIZABLE DEVELOPER MATERIAL HAVING AN INDUCED ELECTROSTATIC CHARGE SUCH THAT IT WILL BE ATTRACTED TO THE SURFACE OF THE SUBSTRATE. AFTER THE POWDER PARTICLES ARE PREFERABLY FIXED OR FUSED ON THE SUBSTRATE, IT IS HEATED TO A TEMPERATURE IN EXCESS OF THE GLASS TRASITION TEMPERATURE OF THE FUSED POWDER PARTICLES THEREON AND SUBJECTED TO AN INDUCED ELECTRIC FIELD TO POLARLIZE THE PARTICLES INTO ELECTRETS. THE ELECTRETS ARE THEN CONTACTED BY ADDITIONAL ELECTROSTATICALLY CHARGED POWDER PARTICLES IN THE SAME MANNNER AS WAS THE ORIGINAL LATENT ELECTROSTATIC IMAGE SO THAT THE DEVELOPED IMAGE DENSITY IS ENHANCED DUE TO THE ADDITIONAL POWDER PARTICLES ATTRACTED TO THE SUBSTRATE.

Aug. 6, 1974 N w, H 4 3,827,905

DEVELOPMENT ENHANCEMENT OF ELECTROSTATIC IMAGES Filed July9. 1971 l3 I5l3 9 l3 l 1 H II H FIG. IA FIG. IB FIG. IC

I 28 f 29 l9a 1 iti II 3 /PI lg 23 v T OVEN T T919 FIG. 2

9 e e 9 as FIG. 3A FIG. 3B

INVENTOR.

WALTER ROTH SOKOLSKI a WOHLGEMUTH ATTORNEYS United States Patent US. Cl.117-175 17 Claims ABSTRACT OF THE DISCLOSURE A process of enhancing thedevelopment of latent electrostatic images on a substrate whichcomprises contacting the latent image with a powdered pigmented, fusibleand polarizable developer material having an induced electrostaticcharge such that it will be attracted to the surface of the substrate.After the powder particles are preferably fixed or fused on thesubstrate, it is heated to a temperature in excess of the glasstransition temperature of the fused powder particles thereon andsubjected to an induced electric field to polarize the particles intoelectrets. The electrets are then contacted by additionalelectrostatically charged powder particles in the same manner as was theoriginal latent electrostatic image so that the developed image densityis enhanced due to the additional powder particles attracted to thesubstrate.

BACKGROUND OF THE INVENTION This invention relates to the development oflatent electrostatic images which have been formed on electricallyinsulative substrates. More particularly, the invention relates toenhancing the optical density of developed electrostatic images.

The general process known as ionography is a means for making X-rayimages without the utilization of silver halide film. The basic processwas disclosed by E. L. Criscuolo in NAVORD Report 4033 of July 6, 1955,in US. Pat. 2,900,515, in an article by R. A. Youshaw and J. A. Hollowayin Nondestructive Testing, September- October 1959, and by K. H. Reissin Z. Angew. Physik, Vol. 19, p. 1 (1965). This process comprises theutilization of two parallel plate electrodes. A DC. voltage is appliedacross the electrodes such that one is a positive electrode and theother a negative one. When the positive electrode is nearest the X-raybeam it must not absorb much of the X-ray beam. It has affixed to it animage receiving sheet which may be transparent or opaque but must be anelectrical insulator such as a thin sheet of a plastic film or the like.The negative electrode has a thin film or layer of a material which isan efficient absorber of X-rays applied to it. In the aforementionedReiss reference a heavy metal, such as lead, tungsten or molybdenum wasutilized as an absorber of the X-rays, and was in eiiect a photoemitter.The image receiving insulator on the anode and the photoemitter layer onthe cathode face each other across the gap between the electrodes withthe object being examined disposed on either the outer side of the anodeor cathode, preferably on the outer side of the anode. A quenching gasis flowed, or in cases may be stationary, in the gap between theelectrodes.

When an object disposed adjacent the anode is irradiated by X-rays orgamma rays, this electromagnetic radiation is differentially absorbed bythe object and passes through the transmissive anode and insulator layerafiixed thereto and across the gap to strike the photoemitter which, asa consequence, ejects electrons having energies up to many kilo-electronvolts. The number of electrons emitted from any area or portion of thephotoemitter is 3,827,905 Patented Aug. 6, 1974 dependent upon thenumber of X-ray photons absorbed in that portion, the depth of theabsorption, and the photon energy. On leaving the photoemitter surface,the electrons find themselves in a DC field between the electrodes andtravel toward the positive electrode. The quenching gas serves to slowdown the electrons so that they will not scatter when reaching theinsulator and to increase their number by secondary ionization. Uponarriving at the insulator surface, the electrons, and any negative ionswhich may have been formed by attachment to components of the quenchinggas, are collected in an image configuration forming a latentelectrostatic image consisting of negative charges corresponding toelements or portions of the object which are relatively transparent toX-rays and no charge or fewer charges corresponding to portions orelements of the object which are opaque or relatively opaque to X-rays.This latent image is then made visible by development or by cathode raytube display techniques.

The development of the latent electrostatic images is accomplishedgenerally by contacting the latent images with powder particles normallyutilized for developing such images, not only in ionographic processesbut other processes where latent electrostatic images are formed, suchas xerography and the like. Typical developer powder particles includecharcoal, carbon black and various carbonaceous type pigments.Additionally, finely divided material, such as powdered resins, havingpigments or dyes added thereto can be used. The use of such resins isdesired where the formed image is to be ultimately fused by heat orother means. The particle size of the powder material is relativelysmall in order to maintain a good resolution of the developed image. Forexample, particles having average diameters on the order of 1 to 10microns are normally utilized. The latent electrostatic image can eitherhave a positive or negative charge, depending upon the polarity of theadjacent electrode utilized during the process of forming the image.Similarly the powder particles have a charge thereon which can beinduced by means of a corona discharge or in other ways.

If the powder particles have a charge opposite to that of the latentimage, they will then be attracted to the latent image charges forming apositive image. Alternatively, if the powder particles have a charge ofthe same polarity as that of the latent image, they will be repelled bythe latent image and cover the substrate in the ateas not occupied bythe latent image, thus in efiect forming a negative image. Thus thepowder particles are given a charge, either opposite to or the same asthe latent electrostatic charges on the substrate, depending upon thetype of developed image desired.

The density of the developed image is basically affected by the amountof latent electrostatic charge produced on the substrate material.Further, the density can be controlled by the amount of developer powderutilized and there is a generally optimum preferred density for adeveloped image. Further, there is a maximum density that can beachieved and this is determined principally by the strength of theelectrostatic charge of the latent image. Thus, an excess of developerpowder cannot make a latent image any denser than the limitations set bythe latent image. On the other hand, a lesser amount of powder candecrease the density regardless of the amount of the latentelectrostatic charges on the substrate. As has been indicated,ionography involves the utilization of X-rays. The ionographic process,which produces images of portions of the human body in a manner similarto normal X-rays, is particularly useful in mammography. It can beappreciated that the normal X-ray procedure involves a production of aphotographic image whereas in ionography, a like image is produced on aninsulative substrate by latent electrostatic charges which aresubsequently developed.

A particular advantage of ionography, as compared to a normal X-raytechnique, is the ability to produce clear images at lower X-ray doses.As indicated above, the strength of the electrostatic field of thelatent image affects the density of the resulting image, but does notaffect to any great degree the resolution or other imagecharacteristics. As a result, it is desirable to produce opticallydenser images with latent electrostatic images of a given field or levelof charge. This would mean, in effect, that a successful developed imagecould be produced with a shorter X-ray exposure.

SUMMARY OF THE INVENTION Thus, it is an object of this invention toprovide developed images of enhanced optical density from latentelectrostatic images, and to provide high quality developed ionographicimages with shorter X-ray exposures. Other objects and features will bein part apparent and in part pointed out hereinafter.

The above and other objects are accomplished by the novel methods andproducts of this invention in which latent electrostatic images areproduced on insulative substrates, such as by the process of ionography.Such latent electrostatic images are then contacted with pigmentedfusible polarizable particles. However, in accord with the presentinvention, a shorter exposure period of X-ray is required and thus thelatent images formed on the substrate may have a weaker electrostaticcharge so that a lesser amount of powder particles will be attractedthereto. Such images when developed may not have the desired densitypreferred for practical applications. But in accordance with thisinvention, the substrate and the powder particles, after fusion thereonto form an initial visible image (by a conventional technique such asusing heat or other energy sources), are then subjected to an electricfield, e.g., one established between two electrodes. The electrodeadjacent the side of the substrate on which the fused image exists willhave a polarity opposite to the polarity that is induced on the surfaceof the fused image. The substrate and fused polarizable material arethen heated to a temperature above the glass transition point of thepowder material while being subjected to the electric field whichpolarizes the fused material into electrets. This creates an exposedplurality of charges on the surface of the fused initial visible imagewhich have the same polarity as the electrode on which the substrateresides. The electric field is maintained for a period sufficient toform such electrets and the material is then allowed to cool to roomtemperature while the field remains. The substrate with the electretimage is then ex posed to a cloud of additional charged powder particleswhich, as indicated, will have a charge opposite to the charge of thesurface of the electrets so as to be attracted thereto and intensify theoptical density of the initial visible image. This process may be againrepeated after the additional powder has been fused and converted againinto electrets thereby to obtain eventually as dark or as dense a finalvisible image as desired. It can thus be seen that in accordance withthis invention the density of the image is enhanced not by an increasedduration of X-ray exposure or level of X-ray exposure, but rather by theformation of the aforementioned electrets from the developing powderparticles and subsequent development of the electret image withadditional toner particles.

As used herein an electret is a dielectric body possessing separatedelectric poles of opposite sign and of a permanent or semipermanentnature; it is the electrical analog of a permanent magnet.

The expression glass transition temperature is that temperature at whichan amorphous polymer changes from a viscous or rubbery condition to ahard or brittle one, or vice versa.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. lA-lC schematically illustratethe development and fusing of an electrostatic image;

FIG. 2 illustrates a method of this invention for converting the applieddeveloping powder to electrets; and

FIGS. 3A and 3B schematically illustrate the further development andfusing of the electrets formed in FIG. 2.

Corresponding reference characters indicate corresponding elementsthroughout the drawings.

DESCRIPTION OF PREFERRED EMBODIMENTS Turning now to FIGS. 1A--lC, thereis schematically shown an insulative substrate 11 which can, forexample, be of a polyester film, such as sold under the tradedesignation Mylar, or other suitable electrically nonconductivematerial. On the surface 13 of substrate 11 there are a plurality ofpositive charges 15 which form or constitute a latent electrostaticimage thereon. Though positive charges 1-5 are shown, the latentelectrostatic image can be formed of negative charges as well. If theelectrostatic image is formed in an ionographic process, for example,the polarity of the charges will be dependent upon the polarity of thespaced-apart conductive plates utilized in the process, with the chargesbeing of a polarity opposite to that of the conductive plate on whichthe substrate is disposed. Substrate 11 with the electrostatic image 15formed thereon is then ready for a development process which normallycomprises contacting the electrostatic image 15 with a cloud of fineparticles 17 which have been charged to have a polarity opposite to thatof the latent image. Thus, as shown in FIG. 1B, a cloud of negativelycharged particles 17 are illustrated. Once again, this is a conventionaltechnique in the development of electrostatic images. In the presentinvention, powder particles 17 are formed from fusible, polarizableresinous material which has a pigment therein, such as charcoal, lampblack, or the like. Typical such polarizable materials utilized includepolymethyl methacrylate, polyethylene terephthalate,polytetrafiuoroethylene, polystyrene, and polyethylene. Additionally,materials such as paraflin wax, carnauba wax and other waxes arematerials which may be formed or converted into electrets. Generally, itis preferred to use lower melting point resins or material which readilycan be converted into electrets without deleteriously affecting thesubstrate material.

As shown in FIG. 1B, by utilizing toner or developer powder particles 17which are charged to have a polarity opposite to that of the latentimage, the powder will be directly attracted to the latent image andadhere thereto. As an alternate method of developing, the powderparticles 17 are charged so as to have the same polarity as that of thelatent electrostatic image. In that instance, the powder particles willbe repelled by the latent electrostatic image and cover the surface '13of the substrate 11 in the areas not carrying the electrostatic charges,thus in effect forming a negative image. I

Powder particles 17 on substrate surface 13- (as produced in FIG. 1B)are then heated to a temperature sufficient to fuse the resin particlestogether, forming a continuous mound 19 on the substrate surface 13 inthe area of the latent electrostatic image as illustrated in FIG. 1C.This, thus, provides for a continuous line or a continuous dark areawhere the electrostatic image previously existed.

The sequence of steps in FIGS. lA-lC is old and wellknown in the art offorming and developing latent electrostatic images, and is used hereinto comparatively illustrate the initial steps utilized in practicing thepresent invention.

The fused image formed in FIG. 1C, together with the substrate 11 towhich it is 'fused, is then, in accordance with this invention, placedin an oven 21 as seen in FIG. 2. Substrate 11 is disposed between twoparallel plate electrodes 23 and 25, respectively, resting, for example,on the bottommost electrode 23. A power source is connected to theseelectrodes to provide a D0. electric field of about 30,000 v./cm.,across a gap 28 between the plates. As shown in FIG. 2, the uppermostplate 25 is of negative polarity, while the bottommost plate 23 on whichthe substrate 11 rests, is positive. The polarity of the spaced-apartplates is established so as to produce or induce an apparent preferredpolarity within fused resin material 19a such that the outer surface 29of the fused material has a positive charge 31. This results from thedistortion by the electric fiield of the electron distribution aroundthe positive nuclei of the polymer molecules so that there is a netpositive charge in the direction of the negative electrode. Materialswhich behave in this manner are referred to as being polarizable.

Similarly, fused mass 19a will have a negative polarity adjacent thesubstrate 11 due to the fact that the plate 23 is positive. In theembodiment shown in FIG. 2, the positive polarity of the fused mass onits surface is shown since the developing powder 17 as shown in FIG. 1Bis negatively charged. If positively charged developing powder is to beutilized then the electric field would be reversed to cause the polarityof the fused mass at its surface to be negative. In other words, onepurpose of this invention as indicated by FIG. 2, is to provide thefused mass with a plurality of charges or poles at its surface having apolarity opposite to that of the charged developing powder particles sothat the additional developing particles will be attracted thereto forsubsequent development. In order to accomplish this, and as indicated inFIG. 2, the fused mass is heated to a temperature greater than the glasstransition temperature of the resin toner materials Tg utilized, butless than the glass transition temperature of the substrate 11 (Tg Thetemperature relationship is thus shown in FIG. 2. The thusheatedmaterial is subjected to the electric field and cooled thereby formingelectrets of the fused resin material. Thus, in accordance with thisinvention, electrets are formed'from the fused resin particles 19a andthus the entire developed image becomes an electret image with anapparent polarity at its surface and charge sutficinet to attractadditional developing powder.

The required temperature level is maintained in the oven while the fieldis applied for a period of time sufficient to accomplish the electretformation. This period can range from sec. to 30 min. and depends uponthe viscosity of the material and the mobility of the molecules ofpolymer or other electret forming material. The proper length of timefor subjecting the fused material to the electric field and itsmagnitude may be conveniently determined by running a series of tests atdiffering time periods.

Substrate 11 on which is formed the resulting electret image is thenremoved from the oven and further developed as illustrated in FIG. 3Awhere additional powder particles 17 contact the electret image 19a,being particularly attracted by the apparent positive charges 31 on thesurface thereof. The additional toner particles 17 attracted to thesurface are then subjected to a fusing temperature thereby forming anadditional layer 33 on top of the previously fused electret image layer19a. This serves to enhance the optical density of the resulting imagesince there is more developing powder at the side of the image on thesubstrate 11.

The optical density of the images formed is dependent on the amount orthickness of powder on the substrate surface since it is the powderparticles that carry the pigment. In turn, the number of powderparticles attracted is a function of the magnitude of latentelectrostatic charges existing on the substrate. The magnitude ofelectrostatic charges that form the latent image is dependent on thedegree of exposure used to produce them. In ionography, as indicatedabove, the process involves X-rays, or gamma rays striking aphotoemittive surface. By reducing the radiation exposure, either as tothe radiation intensity or the time of time of exposure, there will befewer electrostatic charges formed on the substrate. In turn, theresulting optical image, though well-defined, may not be as dense asdesired, nor as optimized, when the exposure is so cut down. But inaccordance with this invention, developing powder is attracted to thelatent electrostatic image on the substrate in an amount whichcorresponds to an optimum optical or visual image density. As a reducedradiation exposure is employed to produce the latent image and theresulting first fused layer 19 of toner particles, the optical densitythereof is less than desirable. The density is then enhanced by theformation of an electret image and further deposition of a layer 33 ofadditional toner particles as seen in FIG. 3B.

The invention will be further illustrated by the following example:

EXAMPLE An ionographic image of an aluminum ste wedge was made anddeveloped with toner, such as is available under the trade designationXerox type 22 in a powder cloud apparatus and was then fused by exposureto the light from a xenon flashlamp such that the image received anenergy of 8 watt sec/in. for about 1.5 msec. The image was then placedbetween two parallel aluminum electrodes. The image was formed on a .007inch Mylar substrate. One-half of the image was backed with anadditional strip of seven mil Mylar. A voltage of about 2 kv. wasapplied across the electrodes. The entire assembly was brought to atemperature of C. which is above the glass transition point of thetoner, yet below the glass transition of the Mylar. The temperatureconditions and voltage conditions were maintained for about twentyminutes. During this period, the electrode facing the toner image wasnegative. Then the assembly was cooled to room temperature while thefield was maintained. The substrate and fused image were then subjectedto additional development with the same Xerox toner and againflash-fixed. The portion of the image which was not backed by the stripof Mylar, and which was thus subjected to a higher field, was observedto have an increased optical density over the portion backed by theadditional Mylar strip. Densitometry was performed on the resultingimage. A set of neutral density filters were used to match transmissionof both portions or halves of the image. The half of the image whichreceived a reduced effect from the electrical field had a transmissionof .23, while the other half appeared more intense and had atransmission of .17. These correspond to optical densities of .64 and.77, respectively. Thus, the additional development of the half of theimage which resulted from the conversion to electrets gave a 20%increase in optical density.

Though the above invention has been described relative to use of apowder cloud of toner particles for development of the latent image, anyother technique using charged developer particles would be applicable tothe process of this invention. Thus, for example, liquid developerscould be used where the charged toner particles are dispersed in aliquid medium.

In view of the above, it will be seen that the several objects of theinvention are achieved and other advantageous results attained.

As various changes could be made in the above methods and productswithout departing from the scope of the invention, it is intended thatall matter contained in the above description or shown in theaccompanying drawings shall be interpreted as illustrative and not in alimiting sense.

What is claimed is:

1. The process of claim 7, wherein said electrets comprise dielectricthermoplastic material adapted to be thermally fused to the substrateand are formed by:

heating said polarizable material as arranged in a pattern on saidsubstrate to a temperature above the glass transition temperature of thepolarizable material; and,

subjecting said heated polarizable material to an electrical field andcooling said material below its glass transition temperature thereby toform said electrets.

2. The process of claim 1 wherein said insulative substrate is a resinfilm having a glass transition temperature above that of saidpolarizable material and which further comprises heating saidpolarizable material to a temperature below the glass transitiontemperature of said substrate but above the glass transition temperatureof said polarizable material.

3. The process of claim 1 further comprising placing said heatedpolarizable material between two parallel plate electrodes having a DC.voltage applied thereacross.

4. The process of claim 3 which further comprises applying the DC.voltage across the electrodes so that the polarity of the plateelectrode adjacent the softened polarizable material will have the samepolarity as that of said electrostatically charged developer powderparticles to be subsequently used.

5. A process for improving the developing of a humanreadable imagerepresentation on a substrate comprising:

forming an image comprised of electrets adherently dispersed on asuitable dielectric substrate,

and contacting said electret image with electrostatically chargeddeveloper powder particles to adhere said particles to said electretimage.

6. The process of claim wherein the electrets are thermally fused to asurface of the substrate.

7. A process for enhancing the development of a latent electrostaticimage on an electrically insulative substrate comprising the steps of:

contacting said electrically insulative substrate bearing saidelectrostatic image with developer material comprising electrostaticallycharged powder particles of a softenable polarizable material to developsaid latent electrostatic image,

softening said powder particles on said substrate;

forming said softened particles into electrets by subjecting them to anelectrical field while in the softened state;

contacting said electrets with developer powder particleselectrostatically charged and arranged to adhere to the so-formedelectrets; and

fixing the last said powder particles to form an enhanced visible,usable image on this substrate. 8. The process of claim 7 wherein saiddeveloper material is the same as said developer powder.

9. The process of claim 7 wherein the charged powder particles ofpolarizable material are pigmented.

10. A process for improving the image quality of an image pattern ofpolarizable material disposed upon a relatively electrically insulativesurface comprising:

subjecting the polarizable material to an electric field to formpolarized electret material which presents an attracting field of aprescribed first polarity at the surface of the image pattern, thismaterial being conditioned, while so subjected to this electric field,so as to accommodate this polarization; providing a quantity ofdeveloper powder particles, sufficient at least to contact a substantialportion of the polarized pattern and charged to a prescribed secondpolarity, opposite to said first polarity; and

further developing the polarized electret image pattern by dusting itwith said developer particles so that these particles areelectrostatically attracted to the surface of the pattern andretainedthereon for view- 11. The process of claim 10 wherein the insulativesurface comprises a dielectric material having a softeningcharacteristic which is relatively unaffected by the forming of thepolarized material and wherein the formation of the polarized materialincludes softening it while simultaneously subjecting it to saidelectric field.

12. The process of claim 11 wherein said developer particles arepolarizable and further comprising the additional steps of softeningsaid developer particles in contact with said electret image whilesimultaneously subjecting said developer particles to an electric fieldto thus form an additional, superposed electret image pattern adhered tothe underlying electret pattern and then,

contacting the final uppermost electret pattern layer so formed with afurther layer of electrostatically charged toner particles adapted to beelectrostatically retained thereon and adhered thereto for viewing. 13.The process of claim 11 wherein said developer particles applied as thefinal particle layer are heatfused to the underlying electret particlesto be relatively permanently retained thereon.

14. A method for enhancing the optical density of an image patternformed with electrostatic toner particles on an electrically insulativesubstrate comprising the steps of:

selecting said toner particles to comprise polarizable, dielectricmaterial, at least on the surface thereof;

forming at least a portion of said toner particles, in situ, as disposedin the said image pattern on the substrate, in at least the initiallayer, into electrets, so as to exhibit sufiicient electrostatic chargeto attract and retain a further layer of toner particles thereon, and,then,

applying at least one further layer of electrostatically charged tonerparticles onto this electret pattern, said particles beingelectrostatically charged and adapted to be attracted and retained onthe electret pattern.

15. A product comprising an electrically insulative substate, aplurality of electrets fused to a surface of said substrate in a raiseddiscrete image defining pattern, and a layer of fused developer powderparticles covering said fused electrets.

16. An image rendition comprising an electrically insulative substrate;at least one layer of electret patriculate material disposed on thissubstrate and adhered thereto in a prescribed image pattern;

and a layer of dielectric particulate developer material covering atleast a substantial portion of this electret pattern and adhered thereonto render a visible image.

17. An image pattern for viewing comprising an arrangement of materialdistributed and adhered upon an electrically insulative substrate in thepattern configuration, with at least the surface portion of thismaterial being in a prescribed electret condition; and electrostaticallycharged developer material disposed and charged so as to be retained onat least a substantial portion of the material in this electretcondiiton.

References Cited UNITED STATES PATENTS 3,576,624 4/1971 Matkan 96-1.33,364,020 1/1968 Fehlberg 96-1 R 3,005,707 10/1961 Kallmann et al. 96-1R 3,597,073 8/1971 Grier 961.3 3,598,485 8/1971 Grier 96-1.3 3,666,3655/1972 Tanaka et al. 96-1 R 3,519,461 7/1970 Stowell 117-175 OTHERREFERENCES Pillai et al.: Review article on Thermoelectrets and TheirApplication, Phys. Stat. 801., vol. 13a, pp. 341-51 (1972).

MICHAEL SOFOCLEOUS, Primary Examiner US. Cl. X.R.

v UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION P'atent3,827,905 Dated August 6, 197

Inventor 3 Walter Roth It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

The tabulation of the claims, showing the patent claim number, 'theorder in which the claims should have issued and the originalapplication claim number is shown below:

4 Q r -iginal application Signed and sealed this 17th day of December1974.

(SEAL) .Attest: I a a McCOY M. GIBSON JR. c. MARSHALL DANN AttestingOfficer Commissioner of Patents USCOMM-DC 60376-P69 U.S. GPVERNMENTPRINTING OFFICE! 9. 9 0

FORM PO-IOSO (O-69)-

